The present invention generally relates to electrical connection boxes and more particularly, to an electrical connection box in which tabs of bus bars inside a casing are connected to terminals of a relay or the like outside the casing through relay terminals, respectively.
In an electrical connection box used for connecting wiring harnesses, etc. for a motor vehicle to various electrical devices through branching, a branch connection point is concentrated at a spot such that branch connection of wires is performed reasonably and economically. In response to recent trends towards higher density of the wiring harnesses, various types of electrical connection boxes are developed separately for types of motor vehicles or applications.
In such a known electrical connection box as described above, bus bars each formed by an electrically conductive metal plate are provided in a casing through insulating plates so as to constitute an internal circuit, while a connective portion in which a relay or the like is electrically connected to tabs of the bus bars through relay terminals is provided on an outer face of the casing.
As shown in FIGS. 1 and 2, a known composite relay 1 may include a plurality of terminals 2 and 3 which have an identical length L but have different widths W1 and W2, respectively so as to conform to specifications such as allowable current and the width W1 is larger than the width W2.
Meanwhile, as shown in FIGS. 3 to 5 and FIGS. 6 to 8, relay terminals 4 and 5 used for the terminals 2 and 3, respectively have different lengths L2 and L3, respectively stipulated for the widths W1 and W2 of the terminals 2 and 3 of the relay 1 by standards and the length L2 is larger than the length L3. However, a distance A between an upper face 6b of a bus bar 6 in a casing and a lower face 1a of a relay 1 connected to a connective portion of the casing in FIG. 3 is identical with that of FIG. 6. Therefore, as shown in FIG. 3, the wide terminal 2 can be connected to the long relay terminal 4 over an electrically stable length, while as shown in FIG. 6, the narrow terminal 3 cannot be connected to the short relay terminal 5 over an electrically stable length.
Furthermore, when the relay 1 is attached to or detached from the relay terminal 5, such a problem may arise that the relay terminal 5 moves greatly upwardly and downwardly in the connective portion of the casing, so that length of connection of the relay terminal 5 to a tab 6a of the bus bar 6 changes and thus, the relay terminal 5 cannot be connected to the tab 6a of the bus bar 6 over an electrically stable length.
In order to obviate this inconvenience, another relay terminal 5 which has the length L2 of the relay terminal 4 may be produced additionally. However, in this case, such drawbacks are incurred that production cost of the different relay terminals 5 rises due to production cost for their different dies, etc. and production control of the relay terminals 5 deteriorates through increase of the number of kinds of the relay terminals 5.